v1.3.1

This release includes the following changes and additions:

• General style modifications according to PEP8 (Brandimarte, Frederiksen)
• Code cleanup according to codacy checks (Brandimarte, Frederiksen)
• API documentation initiated (Brandimarte, Frederiksen)
• Inelastica version info included in logfiles (Frederiksen)
• 1D carbon chain test system (Frederiksen)